Gas breakdown with nanosecond pulses

This paper deals mainly with preliminary results obtained by focusing the Oscar-rewarded C.G.E. laser in air and deuterium of moderate pressure. A fast plasma expansion is identified as a breakdown wave. The influence of the initial pressure on propagation speed and light absorption was studied. Breakdown waves were also found in light-matter interaction in high-pressure gas (30-ns laser pulses) and in solid-state dielectrics (short pulses). A theoretical approach is outlined that would permit the achievement of high temperatures, despite the presence of breakdown waves.